Car runs fine with cold and then misfire and bucks when warm/hard start

[Gvr4799]

I just put the motor in. It's a wiring speacialties harness with a blacktop in a 97 240sx. When I first started the it was running so rich it poured out black smoke. I replaced the spark plugs and it made it better. The car will start fine and drive fine when cold. Soon as it warms up, it acts up. It will barely start and it will buck in 2nd gear and break up in 1st.

So far I've done a boost leak test. checked the maf, tps coils, wiring is all plugged up right. I've replaced the coolant temp sensor. Compression is 160 across the board. I've yet to check base timing and will be doing so soon but the cas has what appears to be a factory sticker on bolt that doesn't look like it's been tampered with.

So I'm not sure if it's something I'm over looking. I've researched this issue for four days now and can't come up with a fix.

Any pointers would be greatly appreciated.

[ultimateirving]

You didn't mention if you pulled codes from the Ecu. Also it still sounds like something with the cts. Be sure it matches your sr. S13 and s14 sr have different sensors iirc

[R@ddy]

I had this same issue. Ended up being a bad coolant temp. sensor.

[Gvr4799]

My CEL light has been removed. I'm not sure how to pull them.

I've just found this out a few min ago. I pulled the PCV and it'll fire right up, even warm. Soon as I plugged it back up it killed the car.

https://www.youtube.com/watch?v=h-ODvTczgNQ

[Gvr4799]

That was my guess too. Do you think it's possible I'm wired for the wrong CTS? I just replaced it and it didn't affect anything.
.

[ultimateirving]

I don't know how to explain the pcv killing the car. Strange that a vacuum leak like that helped.
How does she idle when she is warmed up?

[Gvr4799]

It barely runs. Struggles to stay on.

[Gvr4799]

Timing is set. Car still runs fine when cold and soon as any temp comes, it falls on it's face. When warm it's nearly impossible to get started. I unplugged the o2 sensor and then the car will start. When I plugged it back up, it wouldn't. If you look at the pic below, if black is ground then they don't line up. Seeing how this is and aftermarket harness and after market o2, it's hard for me to tell which wire is what.

http://img.photobucket.com/albums/v306/Gvr4799/97%20240sx%20LE/20140709_190226_zps0f538f14.jpg (http://smg.photobucket.com/user/Gvr4799/media/97%20240sx%20LE/20140709_190226_zps0f538f14.jpg.html)

[ultimateirving]

Well you should be able to test the chassis side of the harness. One will be ground the other a 12v heater for the o2 and the third will be the return signal

On your pic the blue is the 12v heater my guess and the other two self explanatory.

[Gvr4799]

PCV has been replaced and it didn't fix the problem. Today, I'm going to pull the IACV and clean it and replace the injector o-rings.

This has been extremely frustrating So hopefully something pans out today.

[Gvr4799]

Now, put in an aftermarket fpr to make sure I was holding pressure, I was holding pressure fine. Pulled the rail and sealed the lowers. Cleaned out the IACV, it appears to be working find and was before. I just got the original o2 sensor that came with the motor back that's a skinny o2 sensor and I'm waiting for the o2 adapter to try that.

I spoke to Yuri at wiring specialties, we're going to test continuity on the coolant temp sensor.

[KoukiMonsta]

CTS is very easy to test. Continuity also. Hope this isn't some wild issue like Kyle has been dealing with.

[Gvr4799]

What type of issues has Kyle been dealing with?

I also checked to make sure the CTS was working. I will keep everyone posted. Hopefully I find a solution soon.

[RickyS13.]

My bucking ended up being my oxygen sensor wiring. Definitely fix the oxygen sensor first, that will cause bucking really bad.

[Gvr4799]

So I put the old o2 sensor in that came with the car. I was running a z32 bosch o2 sensor.

I did find out something new yesterday. If I unplug the MAF, the car will idle perfectly. It idled for over 20 min and was warm. Soon as I plug the MAF back up, it instantly kills the car.

I had my buddy bring over a working MAF in hopes that would be my fix and the other maf did the same exact thing.